Hemoregulatory compounds

ABSTRACT

Novel compounds of the general formula (I) which have hemoregulatory activities and can be used to stimulate haematopolesis and for the treatment of viral, fungal and bacterial infectious diseases ##STR1##

This application claims the benefit of Provisional Application No. 60/006,642 filed Nov. 13, 1995.

FIELD OF THE INVENTION

The present invention relates to novel compounds which have hemoregulatory activities and can be used to stimulate haematopoiesis and for the treatment of viral, fungal and bacterial infectious diseases.

BACKGROUND OF THE INVENTION

The haematopoietic system is a life-long cell renewal process whereby a defined stem cell population gives rise to a larger population of mature, differentiated blood cells (Dexter T M. Stem cells in normal growth and disease, Br Med J 1987; 195: 1192-1194) of at least nine different cell lineages (erythrocytes, platelets, eosinophils, basophils, neutrophils, monocytes/macrophages, osteoclastes and lymphocytes) (Metcalf D. The Molecular Control of Blood Cells, 1988; Harvard University Press, Cambridge, Mass.). The stem cells are also ultimately responsible for regenerating the bone marrow following treatment with cytotoxic agents or following bone marrow transplantation.

The major dose-limiting toxicities of most standard anti-neoplastic drugs are related to bone marrow suppression, which if severe and prolonged, can give rise to life-threatening infectious and haemorrhagic complications. Myelosuppression is predictable and has been reported to be dose-limiting in greater than 50% of single-agent Phase I trials cytotoxic compounds (Merrouche Y, Catimel G, Clavel M. Haematopoietic growth factors and chemoprotectants; should we move toward a two-step process for phase I trials in oncology? Ann Oncol 1993; 4: 471-474). The risk of infection is directly related to the degree of myelosuppression as measured by the severity and duration of neutropenia (Brody G P, Buckley M, Sathe Y S, Freireich E J. Quantitative relationship between circulating leukocytes and infections. with acute leukemia. Ann In Med 1965; 64: 328-334).

The control of haematopoiesis involves the interplay of a variety of cytokines and growth factors during various stages of the haematopoietic cascade, including early pluripotent stem cells and mature circulating effector cells. These regulatory molecules include granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage stimulating factor (GM-CSF), macrophage-colony stimulating factor (M-CSF), and a variety of interleukines which have overlapping, additive and synergistic actions which play major roles in host defence. Mechanistically, this is accomplished by enhancing the production of granulocytes and macrophages, as well as by the activation of effector cell functions (Moore MAS. Haematopoietic growth factor interactions: in vitro and in vivo preclinical evaluation. Cancer Surveys 1990; 9: 7-80). These co-ordinated activities support optimal host defences which are necessary for fighting bacterial, viral and fungal infections.

Strategies to prevent or reduce the severity of neutropenia and myelotoxicity include the use of haematopoietic growth factors and/or other haematopoietic cytokines. Such treatments are becoming common practice, in that they offer the potential of increased doses of cytotoxic agents that may improve the therapeutic efficacy if antineoplastic agents, and reduce the morbidity associated with their use (Steward W P. Granulocyte and granulocyte-macrophage colony stimulating factors, Lancet 1993; 342: 153-157). Clinical studies have demonstrated the G-, GM- and/or M-CSF may reduce the duration of neutropenia, accelerate myeloid recovery and reduce neutropenia-associated infections and other infectious complications in patients with malignancies who are receiving cytotoxic chemotherapy or in high infectious-risk patients following bone marrow transplantation (Steward W P. Granulocyte and granulocyte-macrophage colony stimulating factors, Lancet 1993; 342: 153-157 and Munn D H, Cheung N K V. Preclinical and clinical studies of macrophage colony-stimulating factor. Semin Oncol 1992; 19: 395-407).

We have now found certain novel compounds which have a stimulative effect on myelopoietic cells and are useful in the treatment and prevention of viral, fungal and bacterial diseases.

SUMMARY OF THE INVENTION

This invention comprises compounds, hereinafter represented as Formula (I), which have hemoregulatory activities and can be used to stimulate haematopoiesis and in the prevention and treatment of bacterial, viral and fungal diseases.

These compounds are useful in the restoration of leukocytes in patients with lowered cell counts resulting from a variety of clinical situations, such as surgical induced myelosuppression, AIDS, ARDS, congenital myelodysplacis, bone marrow and organ transplants; in the protection of patients with leukopenia from infection; in the treatment of severely burned patients and in the amelioration of the myelosuppression observed with some cell-cycle specific antiviral agents and in the treatment of infections in patients who have had bone marrow transplants, especially those with graft versus host disease, in the treatment of tuberculosis and in the treatment of fevers of unknown origin in humans and animals. The compounds are also useful in the treatment and prevention of viral, fungal and bacterial diseases, particularly Candida, Herpes and hepatitis in both immunosuppressed and "normal" subjects.

These compounds may also be used in combination with the monomers of co-pending U.S. application Ser. No. 07/799,465 and U.S. Pat. No. 4,499,081, incorporated by reference herein, to provide alternating peaks of high and low activity in the bone marrow cells, thus augmenting the natural circadian rhythm of haematopoiesis. In this way, cytostatic therapy can be given at periods of low bone marrow activity, thus reducing the risk of bone marrow damage, while regeneration will be promoted by the succeeding peak of activity.

This invention is also a pharmaceutical composition, which comprises a compound of Formula (I) and a pharmaceutically acceptable carrier.

This invention further constitutes a method for stimulating the myelopoietic system of an animal, including humans, which comprises administering to an animal in need thereof, an effective amount of a compound of Formula (I).

This invention also constitutes a method for preventing and treating viral, fungal and bacterial infections including sepsis in immunosuppressed and normal animals, including humans, which comprises administering to an animal in need thereof, an effective amount of a compound of Formula (I).

DETAILED DESCRIPTION OF THE INVENTION

The compounds of the invention are represented by structural Formula I ##STR2## wherein: A₁ and A₂ independently from each other denote a group Z-(CH₂)_(k) -(NR'")_(q) ; wherein

Z is a 4-10 membered mono- or bicyclic heterocyclic ring system containing up to four heteroatoms N, O, S in the ring in which at least one heteroatom is N, and wherein the ring is substituted or unsubstituted by one or two C₁₋₄ alkyl, F, Cl, Br, I, C₁₋₄ alkoxy, (CH₂)_(m) R₄, oxo, oxime, O--C₁₋₄ alkyloxime, hydroxy, N(R₃)₂, acylamino or aminoacyl groups, 8, 9, 10 membered monocyclic ring systems being excluded;

R' and R" are independently hydrogen, C₁₋₄ alkylC(O)R₄, C₁₋₄ alkyl or R' and R" are benzyl which is optionally substituted by one or two C₁₋₄ alkyl, C₁₋₄ alkoxy, F, Cl, I, Br, OH, or N(R₃)₂ ;

k is an integer from 0 to 4;

R'" denotes Hydrogen, C₁₋₄ -alkyl or C₁₋₄ -alkylcarboxylic acid;

q is an integer from 0 to 1;

Q denotes a group ##STR3## wherein: B₁ denotes halogen, --(CH₂)_(m) --CN, --(CH₂)_(m+1) --R², --(CH₂)_(m) --R³, --(CH₂)_(m) --COR² or --(CH₂)_(m) --COR³ ; where

R² denotes --OR³, --N(R³)2, --SR³ ;

R³ is independently hydrogen, C₁ -C₄ -alkyl or benzyl;

m is an integer from 0 to 4;

C₁ denotes halogen, --(CH₂)_(n) --CN, --(CH₂)_(n+1) --R⁴, --(CH₂)_(n) --R⁵, --(CH₂)_(n) --COR⁴ or --(CH₂)_(n) --COR⁵ ; where

R⁴ is independently --OR⁵, --N(R⁵)2, --SR⁵ ;

R⁵ is independently hydrogen, C₁ -C₄ -alkyl or benzyl;

n is independently an integer from 0 to 4;

B₂ denotes halogen, --(CH₂)_(k) --CN, --(CH₂)_(k+1) --R⁶, --(CH₂)_(k) --R⁷, --(CH₂)_(k) --COR⁶ or --(CH₂)_(k) --COR⁷ ; where

R⁶ is independently --OR⁷, --N(R⁷)₂, --SR⁷ ;

R⁷ is independently hydrogen, C₁ -C₄ -alkyl or benzyl;

k is an integer from 0 to 4;

C₂ denotes halogen, --(CH₂)_(l) --CN, --(CH₂)_(l+1) -R⁸, --(CH₂)_(l) --R⁹, --(CH₂)_(l) --COR⁸ or --(CH₂)_(l) --COR⁹ ; where

R⁸ is independently --OR⁹, --N(R⁹)₂, --SR⁹ ;

R⁹ is independently hydrogen, C₁ -C₄ -alkyl or benzyl;

1 is an integer from 0 to 4;

D denotes --(CH₂)_(x) --E--(CH₂)_(y) --; wherein

E denotes a single bond or --C═C--, --C.tbd.C--, or --NH--, --O--, ##STR4## --S--or --S--S--; and

x and y independently denote an integer from 0 to 5, with the proviso that

x and y are not 0 if E denotes --NH, --O--, --S-- or --S--S--; with the proviso that B₁ is not identical to C₁ and B₂ is not identical to C₂ ;

A₁ ≠A₂ ;

B₁ ≠B₂ ;

C₁ ≠C₂ ;

B₁ ≠C₁ ; and

B₂ ≠C₂ ;

and pharmaceutically acceptable salts thereof.

Z in the above Formula (I) denotes an optionally substituted pyrrolyl, isopyrrolyl, pyrazolyl, isoimidazolyl, triazolyl, iosxazolyl, oxazolyl, thiazolyl, isothiazolyl, oxadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, pyrrolidinyl, piperazinyl, triazinyl, morpholinyl, indolyl, indoleninyl, isobenzazolyl, pyrindinyl, ioindazolyl, indoxazinyl, benzoxazolyl, quinolinyl, isoquinolinyl, cinnolinyl, quinazolinyl, naphthyridinyl, pyridopyridinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, quinoxalinyl, indolinyl, pyrrolidonyl, imidazolyl, imidazolidinyl, imidazolinyl, piperidyl, tetrazolyl, quinuclidinyl, azetidinyl, or purinyl;

Possible substituents for Z are C₁₋₄ -alkyl, C₁₋₄ -alkoxy, C₁₋₄ -alkoxy-C₁₋₄ -alkyl, oxo, oxime, O--C₁₋₄ -alkyloxime, hydroxy, amino, C₁₋₄ -alkylamino, di-C₁₋₄ -alkylamino, acylamino and aminoacyl.

R' and R" denote hydrogen, methyl, ethyl, propyl, butyl, C₁₋₄ -alkylcarboxylic acid or C₂₋₄ -alkylhydroxy.

R³, R⁵, R⁷ and R⁹ independently denote hydrogen, methyl, ethyl, propyl, i-propyl, butyl and benzyl.

Preferred compounds are those wherein Z is pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, quinolinyl, tetrahydroquinolinyl, azetidinyl, or pyrrolidinyl;

More preferred compounds are those wherein Z is 2-pyridinyl, 2-pyrimidinyl, 2-pyrazinyl, 2-pyrrolidon-5-yl, or pyrrolidinyl.

Preferred substituents for Z are methyl, ethyl, methoxy, methoxymethyl, oxo, oxime, hydroxy, amino, ethylamino or dimethylamino.

Preferred groups R', R", B₂ and C₂ are hydrogen, methyl and ethyl.

Allyl groups may be straight or branched.

The compounds of the present invention may contain one ore more asymmetric carbon atoms and may exist in racemic and optically active forms. All the compounds and diastereomers are contemplated to be within the scope of the present compounds.

Especially preferred compounds are: ##STR5##

Methods of Preparation

Compounds of Formula (I) wherein E, R', R", R'", C₁, C₂, B₁, B₂, A₁, A₂, Z, k, l, m, n, p, x and y are defined as in Formula (I) are prepared by methods analogous to those described in Scheme 1. ##STR6## a) butyllithium, THF; b) NaN₃, NBu₄ I, DMF; c) triphenylphosphine, H₂ O/THF;

d) DMAP, HOBt, EDC, CH₂ Cl₂ ; e) conc. HCl, dioxane/EtOH; f) NAOH, dioxane/H₂ O/EtOH

One equivalent of (2S)-2,5-dihydro-3,6-diethoxyisopropylpyrazine (1 in Scheme 1) is coupled with an appropriate dielectrophile, such as 2 in Scheme 1, using a strong base (such as butyllithium) in a suitable solvent (such as THF) to give 3 in Scheme 1. Chemical group transformation with NaN₃ and NBu4I in a suitable solvent (such as DMF) and subsequent reduction of the resulting azide with triphenylphosphine in suitable polar protic solvents (such as H₂ O/THF) gives 4 in Scheme 1, which is then acylated with an appropriate heterocyclic acid, such as 5 in Scheme 1, using an activating agent (such as EDC) in an aprotic polar solvent (such as CH₂ Cl₂). Hydrolysis and opening of the pyrazine-ring under standard acidic conditions (such as conc. HCl) in a suitable solvent (such as dioxane/ethanol) and subsequent acylation of the resulting amine according to method d) gives 7 in Scheme 1. Optional hydrolysis of the ester under standard basic conditions (such as NaOH) in a suitable solvent (such as dixane/ethanol) furnishes the product 8 in Scheme 1.

In order to use a compound of the Formula (I) or a pharmaceutically acceptable salt thereof for the treatment of humans and other mammals it is normally formulated in accordance with pharmaceutical practice as a pharmaceutical composition.

According to a still further feature of the present invention there are provided pharmaceutical compositions comprising as active ingredient one or more compounds of Formula (I) as herein before defined or physiologically compatible salts thereof, in association with a pharmaceutical carrier or excipient. The compositions according to the invention may be presented for example, in a form suitable for oral, nasal, parenteral or rectal administration.

As used herein, the term "pharmaceutical" includes veterinary applications of the invention. These peptides may be encapsulated, tableted or prepared in an emulsion or syrup for oral administration. Pharmaceutically acceptable solid or liquid carriers may be added to enhance or stabilize the composition, or to facilitate preparation of the composition. Liquid carriers include syrup, peanut oil, olive oil, glycerin, saline and water. Solid carriers include starch, lactose, calcium sulfate dihydrate, terra alba, magnesium stearate or stearic acid, talc, pectin, acacia, agar or gelatin. The carrier may also include a sustained release material such as glyceryl monostearate or glyceryl distearate, alone or with a wax. The amount of solid carrier varies, but, preferably will be between about 20 mg to about 1 g per dosage unit. The pharmaceutical preparations are made following the conventional techniques of pharmacy involving milling, mixing and filling for hard gelatin capsule forms. Capsules containing one or several active ingredients may be produced, for example, by mixing the active ingredients with inert carriers, such as lactose or sorbitol, and filling the mixture into gelatin capsules. Organ specific carrier systems may also be used.

Alternately pharmaceutical compositions of the peptides of this invention or derivatives thereof, may be formulated as solutions of lyophilized powders for parenteral administration. Powders may be reconstituted by addition of a suitable diluent or other pharmaceutically acceptable carrier prior to use. The liquid formulation is generally a buffered, isotonic, aqueous solution. Examples of suitable diluents are normal isotonic saline solution, standard 5% dextrose in water or buffered sodium or ammonium acetate solution. Such formulation is especially suitable for parenteral administration, but may also be used for oral administration and contained in a metered dose inhaler or nebulizer for insufflation. It may be desirable to add excipients such as polyvinylpyrrolidone, gelatin, hydroxycellulose, acacia, polyethylene glycol, mannitol, sodium chloride or sodium citrate.

For rectal administration, a pulverized powder of the peptides of this invention may be combined with excipients such as cocoa butter, glycerin, gelatin or polyethylene glycols and molded into a suppository. The pulverized powders may also be compounded with oily preparation, gel, cream or emulsion, buffered or unbuffered, and administered through a transdermal patch.

Nasal sprays may be formulated similarly in aqueous solution and packed into spray containers either with an aerosol propellant or provided with means for manual compression.

Dosage units containing the compounds of this invention preferably contain 0.05-50 mg, for example 0.05-5 mg of the compound of Formula (I) or of the salt thereof.

According to a still further feature of the present invention there is provided a method of stimulation of myelopoiesis which comprises administering an effective amount of a pharmaceutical composition as hereinbefore defined to a subject.

No unacceptable toxicological effects are expected when compounds of the invention are administered in accordance with the present invention.

The biological activity of the compounds of Formula (I) is demonstrated by the following tests.

Induction of Hematopoietic Synergistic Activity in Stromal Cells

The murine bone marrow derived from stromal cell line C6.4 is grown in 12 well pates in RPMI 1640 with 10% FBS. Upon reaching confluence, the C6.4 cells are washed and the media exchanged with fresh RPMI 1640 without FBS. Confluent cell layers of murine C6.4 cells are treated with compound. Cell free supernatants are collected 18 hours later. Supernatants are fractionated with a Centricon-30 molecular weight cut-off membrane. C6.4 cell hematopoietic synergistic factor (HSF) activity is measured in a murine CFU-C assay.

CFU-C Assay

Bone marrow cells are obtained from C57B 1/6 female mice and suspended in RPMI 1640 with 10% FBS. Bone marrow cells (7.5E+4 cells/mL) are cultured with sub optimal levels of CFU plus dilutions of test C6.4 cell 30K-E supernatants from above in a standard murine soft agar CFU-C assay. Cell aggregates >50 cells are counted as colonies. The number of agar colonies counted is proportional to the amount of HSF present within the C6.4 bone marrow stromal line supernatant.

Effector Cell Function Assay

Female C57B1 mice are administered test compound PO daily for 8 days. Resident peritoneal exudate cells (PEC) utilized ex vivo from treated or untreated mice are harvested with cold calcium and magnesium-free DPBS supplemented with heparin and antibiotics within 2-4 hours following the last injection. Adherent PEM populations are prepared by incubating standardized PEC suspensions in microtiter dishes for 2 hours at 37° C. (5% CO₂) and removing nonadherent cells by washing the wells with warm buffer.

The superoxide dismutase-inhibitable (SOD) superoxide released by effector cells in response to a in vitro stimulation by phorbol myristate acetate (PMA) (100-200 nM) or pre-opsonized (autologous sera) live C. albicans (E:T=1:10) are quantitated in a microtiter ferricytochrome c reduction assay. The assay is performed in the presence of 1% gelatin BSS and 80 μM ferricytochrome c in a total volume of 200 μL/well. The nmoles of cytochrome c reduced/well is calculated from spectrophotometric readings (550 nm) taken following a 1 hour incubation at 37° C. (5% CO₂). The amount of SOD-inhibitable cytochrome c reduced is determined by the inclusion of wells containing SOD (200 U/well). Baseline superoxide release is determined in the absence of stimuli. Experimental data are expressed as a percentage of the control group.

EXAMPLE 1 (2,7)-Bis-(2-pyridylcarbonylamino)-(2R)-heptanoic acid ##STR7## Preparation of 1-((2S,5R)-2,5-dihydro-3,6-diethoxy-2-isopropyl-5-pyrazinyl)-5-bromo-pentane ##STR8## (2S)-2,5-Dihydro-3,6-diethoxyisopropylpyrazine (4.0 g, 18.9 mmol) was dissolved in 50 ml THF and a 1.6 M solution of butyllithium in hexane was added at -78° C. (11.7 ml, 18.9 mmol). After 30 min at -78° C. a solution of 1,5-dibromopentane (4.3 g, 18.9 mmol) in 20 ml THF was added dropwise and the mixture came to room temperature overnight. After hydrolysis the mixture was extracted with diethyl ether (3×200 ml) and the combined organic layers were dried over MgSO₄. After filtration the solvent was removed on the rotary evaporator and the residue was dried under vacuum. The product was purified by flash chromatography (silica gel, petrolether/ethyl acetate 9/0.5). Yield: 44% colorless oil.

Preparation of 1-((2S,5R)-2,5-dihydro-3,6-diethoxy-2-isopropyl-5-pyrazinyl)-5-azido-pentane ##STR9##

1-((2S,5R)-2,5-dihydro-3,6-diethoxy-2-isopropyl-5-pyrazinyl)-5-bromo-pentane (5.3 g,14.6 mmol) was dissolved in 45 ml abs. DMF and NaN₃ (2.85 g, 43.9 mmol) and 0.1 g NBu₄ I were added. The mixture was heated to 70° C. for 12 h in an argon atmosphere. After cooling 60 ml water were added and the reaction mixture was extracted 3× with CH₂ Cl₂. After drying over MgSO₄ the solution was filtered and the solvent removed in vacuum. The residue was purified by flash chromatography (silica gel, petrolether/ethyl acetate 9/0.5). Yield: 84.5% colorless oil.

Preparation of 1-((2S ,5R)-2,5-dihydro-3,6-diethoxy-2-isopropyl-5-pyrazinyl)-5-amino-pentane ##STR10##

1-((2S,5R)-2,5-dihydro-3,6-diethoxy-2-isopropyl-5-pyrazinyl)-5-azido-pentane (2.60 g, 8.04 mmol) was dissolved in 15 ml THF, and water (0.58 g, 32 mmol), followed by a solution of triphenylphosphine (2.53 g, 9.65 mmol) in 5 ml THF was added. The mixture was stirred at room temperature overnight and refluxed for 1 h. After removal of the solvent the residue was purified by flash chromatography (silica gel, chloroform/MeOH/aqueous ammonia 1/2/0.1).Yield: 85.4% pale yellow oil.

Preparation of 1-((2S,5R)-2,5-dihydro-3,6-diethoxy-2-isopropyl-5-pyrazinyl)-5-(2-pyridylcarbonylamino)-pentane ##STR11##

1-((2S,5R)-2,5-dihydro-3,6-diethoxy-2-isopropyl-5-pyrazinyl)-5-amino-pentane (1.00 g, 3.36 mmol), picolinic acid (0.43 g, 3.50 mmol), DMAP (0.43 g, 3.50 mmol) and HOBt (0.632 g, 4.0 mmol) were dissolved in 40 ml CH₂ Cl₂ and cooled to 0° C. EDC (0.67 g, 3.50 mmol) was added and the reaction mixture came to room temperature overnight. It was extracted with 4% aqueous NaHCO₃ solution and dried over MgSO4. After filtration the solvent was removed on the rotary evaporator and the residue was dried under vacuum. The product was purified by flash chromatography (silica gel,chloroform/ethyl acetate 9/1).Yield: 68.5% colorless oil.

Preparation of 2-amino-7-(2-pyridylcarbonylamino)-(2R)-ethylheptanoate ##STR12##

1-((2S,5R)-2,5-dihydro-3,6-diethoxy-2-isopropyl-5-pyrazinyl)-5-amino-pentane (1.13 g, 2.81 mmol) was dissolved in a mixture of 10 ml dioxane and 20 ml EtOH and a solution of conc. HCl (1.0 ml, 12.0 mmol) in 20 ml water was added. The mixture was stirred over the weekend and then concentrated to 20 ml. conc. ammonia solution was added until pH 9 was reached and the solution was extracted with chloroform (3×30 ml). The combined organic layers were dried over MgSO₄. After filtration the solvent was removed on the rotary evaporator and the residue was dried under vacuum. The ValOEt was removed by bulb-to-bulb distillation (0.01 Torr, rt to 50° C.). The residue was used without further purification. Yield: 93% pale yellow oil.

Preparation of (2,7)-Bis-(2-pyridylcarbonylamino)-(2R)-ethylheptanoate ##STR13##

2-Amino-7-(2-pyridylcarbonylamino)-(2R)-ethylheptanoateoat (0.76 g, 2.59 mmol), picolinic acid (0.64 g, 5.2 mmol) and HOBt (0.82 g, 5.2 mol) were dissolved in 20 ml CH₂ Cl₂ and cooled to 0° C. EDC (1.00 g, 5.2 mmol) was added and the reaction mixture came to room temperature overnight. Then it was extracted with 4% aqueous NaHCO₃ solution and dried over MgSO₄. After filtration the solvent was removed on a rotary evaporator and the residue was dried under vacuum. The product was purified by flash chromatography (silica gel,chloroform/ethyl acetate 9/2).Yield 100% colorless oil

Preparation of (2,7)-Bis-(2-pyridylcarbonylamino)-(2R)-heptanoic acid

(2,7)-Bis-(2-pyridylcarbonylamino)-(2R)-ethylheptanoate (0.81 g, 2.04 mmol) was dissolved in a mixture of 3 ml dioxane, 3 ml EtOH and 5 ml water and cooled to 0° C. 1.02 ml 2 N NaOH (2.04 mmol) was added and the mixture came to room temperature overnight. The organic solvents were stripped off and the residual solution was acidified to pH 3 by dropwise addition of 1 N HCl. The mixture was extracted with ethyl acetate (6×25 ml), the combined organic layers were dried over MgSO₄, filtered and the solvents were evaporated. The residue was purified by flash chromatography (silica gel/CHCl₃ /MeOH/HOAc 9/1/0.25). The purified compound was lyophilized. Yield: 85% lyophilisate

¹ H NMR (400 MHz, d₆ -DMSO) d 8.67 (m, 3 H), 8.60 (m, 1 H), 8.00 (m, 4 H), 7.61 (m, 1 H), 7.55 (m, 1 H), 4.46 (m, 1 H), 3.27 (q, 2 H, J=6.7 Hz), 1.86 (m, 2 H), 1.52(m,2 H), 1.34(m,4 H); ¹³ C NMR (100 MHz, d₆ -DMSO) d 173.4, 163.8, 163.7, 150.3, 149.5, 148.7, 148.5, 138.0, 137.8, 126.9, 126.4, 122.0, 121.9, 52.2, 38.9, 31.2, 29.1, 26.2, 25.2;

EXAMPLE 2 (2,7)-Bis-(2-pyridylcarbonylamino)-(2R)-ethylheptanoate

Synthesis of (2,7)-bis-(2-pyridylcarbonylamino)-(2R)-ethylheptanoate was performed analogous to the methods in Example 1, except that the last step (hydrolysis of the ester) was omitted.

¹ H NMR (400 MHz, CDCl₃) d 8.57 (m, 1 H), 8.51 (m, 1 H), 8.46 (d, 1 H, J=8.0 Hz), 8.16 (m, 2 H), 8.04 (br s,1 H), 7.82 (m, 2 H), 7.40 (m, 2 H), 4.78 (m, 1 H), 4.21(q, 2 H, J=7.1Hz), 3.44 (q, 2 H, J=6.5 Hz), 1.98 (m, 1 H), 1.85 (m, 1 H), 1.63 (m, 2 H), 1.44 (m, 4 H), 1.28 (t, 3 H, J=7.0 Hz); ¹³ C NMR (100 MHz, CDCl₃) d 172.2, 164.3, 164.1, 150.1, 149.5, 148.3, 148.0, 137.3, 137.2, 126.3, 126.0, 122.3, 122.2, 61.4, 52.3, 39.3, 32.6, 29.5, 26.7, 25.1, 14.2;

EXAMPLE 3 (2,6)-Bis-(2-pyridylcarbonylamino)-(2R)-hexanoic acid

Synthesis of (2,6)-bis-(2-pyridylcarbonylamino)-(2R)-hexanoic acid was performed analogous to the methods in Example 1.

¹ H NMR (400 MHz, d₄ -MeOH) d 1.44 (m, 4 H), 1.84-1.93 (m, 1 H), 2.00-2.08 (m, 1 H), 3.24 (t, 2 H, J=6.9 Hz), 3.35 (s, 2 H), 4,51 (dd, 1 H, J=5.0, 6.9 Hz), 7.29 (ddd, 1 H, J=1.0, 4.9, 7.4 Hz), 7.39 (ddd, 1 H, J=1.0, 4.9, 7.4 Hz), 7.78 (dt, 1 H, J=1.9, 7.8 Hz), 7.98 (dt, 1 H, J=1.9, 7.8 Hz), 8.12 (dt, 1 H, J=0.8, 7.8 Hz 8.46 (ddd, 1 H, J=0.9, 1.9,4.9 Hz), 8.66 (ddd, 1 H, J=0.9, 1.9,4.9 Hz); ¹³ C NMR (100 MHz, d₄ -MeOH) d 24.3, 30.4, 34.4,40.9, 48.7, 56.5, 123.2, 123.8, 125.6, 127.9, 139.0, 150.1, 151.5, 157.2, 165.9, 172.4, 178.7; 

We claim:
 1. A compound of Formula (I) ##STR14## wherein: A₁ and A₂ independently from each other denote a group Z--(CH₂)_(k) --(NR'")_(q) ; whereinZ is 2-pyridinyl or pyridopyridinyl wherein the heterocycle is substituted or unsubstituted by one or two C₁₋₄ alkyl, F, Cl, Br, I, C₁₋₄ alkoxy, (CH₂)_(m) R₄, oxo, oxime, O--C₁₋₄ alkyloxime, hydroxy, N(R₃)₂, acylamino or aminoacyl groups, R' and R" are independently hydrogen, C₁₋₄ alkylC(O)R₄, C₁₋₄ alkyl or R' and R" are benzyl which is optionally substituted by one or two C₁₋₄ alkyl, C₁₋₄ alkoxy, F, Cl, I, Br, OH, or N(R₃)₂ ; k is an integer from 0 to 4; R'" denotes Hydrogen, C₁₋₄ -alkyl or C₁₋₄ -alkylcarboxylic acid; q is an integer from 0 to 1; Q denotes a group ##STR15## wherein: B₁ denotes halogen, --(CH₂)_(m) --CN, --(CH₂)_(m+1) --R², --(CH₂)_(m) --R³, --(CH₂)_(m) --COR² or --(CH₂)_(m) --COR³ ; where R² denotes --OR³, --N(R³)₂, --SR³ ; R³ is independently hydrogen, C₁ -C₄ -alkyl or benzyl; m is an integer from 0 to 4; C₁ denotes halogen, --(CH₂)_(n) --CN, --(CH₂)_(n+1) --R⁴, --(CH₂)_(n) --R⁵, --(CH₂)_(n) --COR⁴ or --(CH₂)_(n) --COR⁵ ; where R⁴ is independently --OR⁵, --N(R⁵)₂, --SR⁵ ; R⁵ is independently hydrogen, C₁ -C₄ -alkyl or benzyl; n is independently an integer from 0 to 4; B₂ denotes halogen, --(CH₂)_(k) --CN, --(CH₂)_(k+1) --R⁶, --(CH₂)_(k) --R⁷, --(CH₂)_(k) --COR⁶ or --(CH₂)_(k) --COR⁷ ; where R⁶ is independently --OR⁷, --N(R⁷)₂, --SR⁷ ; R⁷ is independently hydrogen, C₁ -C₄ -alkyl or benzyl; k is an integer from 0 to 4; C₂ denotes halogen, --(CH₂)_(l) --CN, --(CH₂)_(l+1) --R⁸, --(CH₂)_(l) --R⁹, --(CH₂)_(l) --COR⁸ or --(CH₂)_(l) --COR⁹ ; where R⁸ is independently --OR⁹, --N(R⁹)₂, --SR⁹ ; R⁹ is independently hydrogen, C₁ -C₄ -alkyl or benzyl; 1is an integer from 0 to 4; D denotes --(CH₂)_(x) --E--(CH₂)_(y) --; wherein E denotes a single bond or --C═C--, --C.tbd.C--, or --NH--, --O--, ##STR16## --S-- or --S--S--; and x and y independently denote an integer from 0 to 5, with the proviso that x and y are not 0 if E denotes --NH, --O--, --S--or --S--S--; with the proviso that B₁ is not identical to C₁ and B₂ is not identical to C₂ ; B₁ ≠B₂ ; and C₁ ≠C₂ ;and pharmaceutically acceptable salts thereof.
 2. A compound of claim 1 wherein Z is 2-pyridinyl.
 3. Compounds according to claim 2 wherein Z is optionally mono-, poly- or mixed substituted by C₁₋₄ -alkyl, C₁₋₄ -alkoxy, C₁₋₄ -alkoxy-C₁₋₄ -alkyl, oxo, oxime, O--C₁₋₄ -alkyloxime, hydroxy, amino, C₁₋₄ -alkylamino, di-C₁₋₄ -alkylamino, acylamino or aminoacyl.
 4. Compounds according to claim 2 wherein Z is optionally mono-, poly- or mixed substituted by methyl, ethyl, methoxy, methoxymethyl, oxo, oxime, hydroxy, amino, ethylamino or dimethylamino.
 5. Compounds according to claim 2 wherein R' and R" independently from each other denote hydrogen, methyl, ethyl, propyl, butyl, C₁₋₄ -alkylcarboxylic acid or C₂₄ -alkylhydroxy.
 6. Compounds according to claim 2 wherein B₁ denotes halogen, --(CH₂)_(m) --CN, --(CH₂)_(m+1) --R², --(CH₂)_(m) --R³, --(CH₂)_(m) --COR² or --(CH₂)_(m) --COR³, where R² denotes --OR³, --NR³ ₂, --SR³, and R³ is hydrogen, methyl, ethyl, propyl, i-propyl, butyl or benzyl and m is an integer from 0 to
 4. 7. Compounds according to claim 2 wherein C₁ denotes halogen, --(CH₂)_(n) --CN, --(CH₂)_(n+1) --R⁴, --(CH₂)_(n) --R⁵, --(CH₂)_(n) --COR⁴ or --(CH₂)_(n) --COR⁵, where R⁴ denotes --OR⁵, --NR⁵ ₂, --SR⁵, and R⁵ is hydrogen, methyl, ethyl, propyl, i-propyl, butyl or benzyl and n is an integer from 0 to
 4. 8. Compounds according to claim 2 wherein B₂ denotes halogen, --(CH₂)_(p) --CN, --(CH₂)_(p+1) --R⁶, --(CH₂)_(p) --R⁷, --(CH₂)_(p) --COR⁶ or --(CH₂)_(p) --COR⁷, where R⁶ denotes --OR⁷, --NR⁷ ₂, --SR⁷, and R⁷ is hydrogen, methyl, ethyl, propyl, i-propyl, butyl or benzyl and p is an integer from 0 to
 4. 9. Compounds according to claim 2 wherein C₂ denotes halogen, --(CH₂)_(l) --CN, --(CH₂)_(l+1) --R⁸, --(CH₂)_(l) --R⁹, --(CH₂)_(l) --COR⁸ or --(CH₂)_(l) --COR⁹, where R⁸ denotes --OR⁹, --NR⁹ ₂, --SR⁹, and R⁹ is hydrogen, methyl, ethyl, propyl, i-propyl, butyl or benzyl and 1 is an integer from 0 to
 4. 10. Compounds according to claim 2 wherein D denotes --(CH₂)_(x) --E--(CH₂)_(y) --, wherein E denotes a single or double bond or, --NH--, --O--, ##STR17## --S-- or --S--S-- and x and y independently denote an integer from 0 to 5, with the proviso that x and y are not 0 if E denotes --NH, --O--, --S-- or --S--S--.
 11. A compound of claim 2 which is:(2,7)-Bis-(2-pyridylcarbonylamino)-(2R)-heptanoic acid (2,7)-Bis-(2-pyridylcarbonylamino)-(2R)-ethylheptanoate (2,6)-Bis-(2-pyridylcarbonylamino)-(2R)-hexanoic acid.
 12. Process for producing a compound as claimed in claim 1, said process comprisinga) reacting one equivalent of a suitably substituted 2,5-Dihydropyrazine with one equivalent of an appropriate dielectrophile; b) replacing a leaving group with an amine; c) acylating this amine with heterocyclic acids; d) hydrolyzing and opening of the pyrazine-ring; e) acylating the resulting amine with heterocyclic acids; f) otionally reducing and/or oxydizing any functional groups and/or removing any remaining protecting groups; and g) optionally forming a pharmaceutically acceptable salt thereof.
 13. A pharmaceutical composition comprising a compound according to claim 1 and a pharmaceutically acceptable carrier.
 14. A method of stimulating the myelopoietic system which comprises administering to a subject in need thereof, an effective amount to stimulate said myelopoietic system of a compound to claim
 1. 15. A method of treating viral, fungal and bacterial infections which comprises administering to a subject in need thereof, an effective amount of a compound of claim
 1. 16. A method of preventing or treating sepsis which comprises administering to a subject in need thereof, an effective amount of a compound of claim
 1. 